TiO2 Based Nanostructures for Photocatalytic CO2 Conversion to Valuable Chemicals

Abstract

Photocatalytic conversion of CO2 to useful products is an alluring approach for acquiring the two-fold benefits of normalizing excess atmospheric CO2 levels and the production of solar chemicals/fuels. Therefore, photocatalytic materials are continuously being developed with enhanced performance in accordance with their respective domains. In recent years, nanostructured photocatalysts such as one dimensional (1-D), two dimensional (2-D) and three dimensional (3-D)/hierarchical have been a subject of great importance because of their explicit advantages over 0-D photocatalysts, including high surface areas, effective charge separation, directional charge transport, and light trapping/scattering effects. Furthermore, the strategy of doping (metals and non-metals), as well as coupling with a secondary material (noble metals, another semiconductor material, graphene, etc.), of nanostructured photocatalysts has resulted in an amplified photocatalytic performance. In the present review article, various titanium dioxide (TiO2)-based nanostructured photocatalysts are briefly overviewed with respect to their application in photocatalytic CO2 conversion to value-added chemicals. This review primarily focuses on the latest developments in TiO2-based nanostructures, specifically 1-D (TiO2 nanotubes, nanorods, nanowires, nanobelts etc.) and 2-D (TiO2 nanosheets, nanolayers), and the reaction conditions and analysis of key parameters and their role in the up-grading and augmentation of photocatalytic performance. Moreover, TiO2-based 3-D and/or hierarchical nanostructures for CO2 conversions are also briefly scrutinized, as they exhibit excellent performance based on the special nanostructure framework, and can be an exemplary photocatalyst architecture demonstrating an admirable performance in the near future.

Photonic–Plasmonic Nanostructures for Solar Energy Utilization and Emerging Biosensors

“…Generally, synergizing structures such as natural porous PCs into the photocatalyst can increase the surface area and porosity for reacting and harvesting photons, respectively. Using a biotemplate based on a green leaf, the morph-TiO 2 exhibiting significantly improved photocatalytic CO 2 conversion was obtained [55]. Moreover, bioinspired structures such as the black scales on the butterfly wings showed enhanced light-harvesting and antireflection ability, which could be artificially fabricated as solar energy conversion systems.…”

Efficient reduction of CO2 to CO by Ag3PO4/TiO2 photocatalyst under ultraviolet and visible light irradiation

“…In the actual reaction system containing H 2 O and CO 2 , the Fermi level of the semi‐conductive Ag 3 PO 4 underwent negative migration, thus the actual CB potential of Ag 3 PO 4 was low enough to reduce CO 2 33,34 . Therefore, in this actual reaction system, the photocatalytic reduction of CO 2 to CO and O 2 can be assumed to occur through the following reactions 5,17 …”

“…Thus, developing other semiconductor‐based photocatalysts such as graphene‐based photocatalysts, 5,6 WO 3 ‐based photocatalysts, 7–10 BiVO 4 ‐based photocatalysts, 11 and the modification of crystalline TiO 2 ‐based catalysts has been studied extensively. Several strategies such as loading noble metals (Pt, Pd, Au, or Ag) 12,13 , non‐noble metals, 14,15 and doping nonmetal elements 5 have been investigated to improve the photocatalytic activity of TiO 2 14,16,17 . It is revealed that metal doping can significantly reduce the recombination rate of photogenerated electron‐hole pairs and the corresponding wavelength can be extended to the visible light region 15 .…”

Recent Developments in Lead and Lead-Free Halide Perovskite Nanostructures towards Photocatalytic CO2 Reduction

“…In any event, the discovery of a new photocatalyst for better synergistic performance has never stopped. To date, several types of catalysts have been employed for CO 2 conversion, including metal oxides, nitrides, sulfides, selenides, chalcogenides, and perovskite materials [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. These materials have made significant progress, but many of them have several drawbacks, such as high-cost synthetic approaches, lengthy/complicated synthesis process, long-term instability, and less catalytic activity.…”